Feline Infectious Peritonitis (FIP) is a highly lethal disease in both wild and domestic cats, occurring predominantly in young animals although cats of all ages are susceptible. Symptoms of FIP may include anemia, neutrophilia, increased concentrations of immunoglobulin and/or fibrinogen, renal damage as indicated by high levels of urea and creatinine, and disseminated intravascular coagulation.
Previous attempts to develop an effective FIPV vaccine have been largely unsuccessful. Administration of traditional inactivated whole virus vaccines have actually predisposed cats to the development of FIP and produced a more rapid and fulminating disease after challenge. Cats vaccinated with an avirulent strain of FIPV were more readily infected than non-immunized cats and animals immunized with a sublethal dose of virulent FIPV showed inconsistent protection from challenge [Pedersen and Black, Am. J. Vet. Res., 44:229-234 (1983)].
Immunization of cats with other antigenically related coronaviruses has also not been successful. In most experiments, the administration of TGEV, CCV and human coronavirus 229E has neither sensitized nor protected cats [Woods and Pedersen, Vet. Microbiol., 4:11-16 (1979); Toma et al, Rec. Med. Vet., 155:788-803 (1979); Barlough et al, Can. J. Comp. Med., 49:303-307 (1985); Barlough et al, Lab. Anim. Sci., 34:592-597 (1984); Stoddart et al, Res. Vet. Sci., 45:383-388 (1988)].
Recently, a temperature-sensitive FIPV (TS-FIPV) vaccine has been developed which, when administered intranasally, is efficacious and safe upon FIPV challenge [Christianson et al, Arch. Virol., 109:185-196 (1989)]. This vaccine has limited efficacy when administered subcutaneously, but appears to be effective against homologous and heterologous strains. Generally, intranasal administration is not preferred because the dosage amount is less quantifiable than other routes.
There remains a need for effective diagnostic, therapeutic and protective compositions for use in diagnosing, treating, and vaccinating animals against FIPV and serologically related infections.